1. Field of the Invention
The present invention relates to an improvement in electrochemical generators such as cells and batteries, which are characterized by high specific energy and further, to a process for manufacturing the same.
2. Description of the Prior Art
It has been recognized that it is desirable to develop cells having a high energy per unit of mass, i.e. a high level of energy density per unit of mass (and per unit of volume). This recognition has led to the use of alkaline metals and in particular of lithium, as anodes for such cells. For instance, it is known to provide cells based on the following anode/cathode systems:
Cu S - Li PA1 Cu Cl - Li PA1 Ag.sub.2 S - Li PA1 Ag Cl - Li PA1 Ag.sub.2 CrO.sub.4 - Li PA1 etc.
These systems are recognized to provide high energy per unit volume, and are therefore particularly advantageous for manufacturing miniature cells. Other pairs, such as LiAl - Fe S, are only effective at very high temperatures, which limit their cycling performance.
The art has also introduced batteries containing solid electrolytes, which have overcome the well known difficulties commonly associated with cells containing aqueous or organic solvents. For instance, with solid state electrolytes there is no difficulty in sealing of the elements, or in thermodynamic instability of the anodes with respect to the solvents. Good solid electrolytes are generally characterized by having a maximum ionic conductivity and a minimum electronic conductivity. All the research work being at present carried out aims at optimizing these two of contradictory parameters.
Furthermore, the introduction on the market of some solid electrolytes based on lithium compounds (see particularly French Patent application No. 80-10531) has made it possible to lower the internal temperature of the cells, thereby making possible lower operating temperatures, which, in turn, permit new lithium based alloys to be used as the anode. Several cells with solid electrolyte and lithium anode are at present in use, but, in general, although cells with a high energy density may be obtained, these cells are limited in the amount of current which can be produced. Therefore, a need has continued to exist for an electrochemical generator having a high current density.